grab bag vs miscellanea

grab bag and miscellanea both are nouns.

Word	Noun	Adjective	Verb	Adverb
grab bag	Yes	No	No	No
miscellanea	Yes	No	No	No

As nouns, miscellanea is a hypernym of grab bag; that is, miscellanea is a word with a broader meaning than grab bag:

Other hypernyms of grab bag include assortment, miscellany, mixed bag, mixture, motley, potpourri, salmagundi, smorgasbord, variety.

grab bag (noun)	miscellanea (noun)
a container from which a person draws a wrapped item at random without knowing the contents	a collection containing a variety of sorts of things
an assortment of miscellaneous items